This invention relates to an apparatus and method for inspecting the edges of metal strip during production. The invention is particularly but not exclusively applicable to the production of hot rolled steel strip.
Steel strip is commonly produced by hot rolling to provide strip typically 1.5 mm to 5.5 mm thick. This strip must then be cleaned and have its edges trimmed before undergoing further processing such as cold rolling and/or coating. The edge trimming is conventionally performed by rotary cutting blades mounted above and below the strip path at either side of the desired width, the blades being rotated by pull-through of the strip.
It is important to obtain a good quality of trimmed edge if the subsequent processing is to be satisfactory. For example, a poor edge may produce small flakes of steel which become trapped between the strip and the rolls of cold rolling mills, damaging both the strip and the rolls. Poor quality edges also cannot be coated satisfactorily in processes such as powder coating.
The nature of the cut edge is determined by the setting of the rotary cutting blades. The upper blade can be adjusted vertically to give a desired degree of radial overlap with the lower blade, while the lower blade can be adjusted in and out to adjust the horizontal gap with the top blade.
It has hitherto been the practice to mount the cutting blade shafts in such a manner that these adjustments must be carried out by the manual adjustment of bolts and the like and the use of spacers and shims. Further, it has been customary to adjust the cutting blades to settings which are thought to be correct, from empirical experience with strip of the same thickness and metallurgical composition, and thereafter to edge trim whole coils of strip. Inspection has been limited to visual inspection of finished coils with the aid only of a hand lens; this can lead to a number of coils having to be scrapped or reworked if the edge quality has become unacceptable, followed by time consuming hand adjustment of the cutting blades on an empirical basis.
A principal object of the present invention is to improve on such prior art processes and apparatus.